Some people enjoy a challenge such as installing a turbo or supercharger on their car/truck/tractor etc.
While I could be wrong it is unlikely much benefit would be derived from increasing the power by turbocharging a lightweight tractor like the 4100 (similar Kubotas etc also). It is unlikely the internals of the unit would be up to the task of the additional horsepower, a larger radiator or fan etc might be needed to reject the additional heat or an oil cooler to help out. Essentially if you need more power you need a bigger tractor. Not only that but there is such a thing as turbo lag, by going with a small turbo and setting the waste gate such that it is kept spooled up lag can be minimized. Soooo, you set the throttle at say 2400 RPM and as you move into the pile of dirt with your FEL the engine begins to lug but then the turbo begins to build boost and the tractor lurches forward and the wheels loose traction and the load on the engine is thus reduced so then the turbo spools out and then the wheels grab hold again loading the engine and the turbo spools back in etc--this is called bootstrapping effect--one thing effects another thing in a sequence. Just get a bigger tractor and leave the experimenting to those who enjoy such things and occasionally have the talent or expertize to make them work.
J